Display devices using piezo-electric transducers



y 966 I s. A. WARD 3,254,264

DISPLAY DEVICES USING PIEZO-ELECTRIC TRANDUCERS Filed July 5, 1961GATING DEVICE INV EN TOR.

United States Patent Filed July 3, 1961, Ser. No. 121,629 20 Claims.(Cl. 315- This invention relates to display devices and moreparticularly to a piezoelectric driven sonoluminescent display panel.

Sonoluminescence, as utilized in my device, may be defined as theluminescence produced'in liquid and semiliquid media when the media isexcited by a sound field or by mechanical vibration.

The prior art luminescent devices have at least one thing in common, andthat is the need for an electric field to sustain light. In oneinstance, when a potential of a suitable amplitude is placed across 'aphosphor material, the phosphor will glow. In another case, where alayer of phosphor or electroluminescent material is placed over a layerof photoconductive material a beam of light directed to a spot on thephotoconductive material will cause it to lower its resistance and applythe electric field to that spot on the luminescent material in registrywith the beam of light. In this manner the luminescent material willproduce light as long as the electric field remains of sufiicientamplitude.

These prior-art devices, while being capable of producing a uniformlight throughout the panel, suffer serious drawbacks when used, forexample, as a gated display medium. To perform in this manner, itbecomes necessary to gate sufficiently small increments in discreetrows. The major ditficulty that is encountered resides in the fact thatas soon as one area of phosphor is excited, the excitation spreads toits adjacent surrounding areas and very rapidly the whole panel becomeslighted. It therefore becomes necessary to devise complex systems toprevent this spill over. More particularly in the case of thephotoconductive electroluminescent device one is also faced with theproblem of devising methods of light feedback within the givenincremental areas while simultaneously preventing the light feedbackfrom triggering the adjacent areas.

My device solves the problems of the prior art in that by utilizingdiscreet piezoelectric elements and sonoluminescent material inconjunction therewith, I am able to produce successive pinpoints oflight throughout given incremental areas without affecting the adjacentareas.

It is, therefore, one .of the primary objects of the present inventionto provide an improved luminescent display panel.

Another important object of the present invention is to provide aluminescent display panel wherein there is no interaction betweenadjacent excited areas.

Still another important object of the present invention is to provide adisplay panel which does not depend on light feedback to produce a spotof light.

The features of my invention which I believe to be novel are set forthwith particularity in the appended claims. The invention itself,however, both as to its organization and method of operation, togetherwith further objects and advantages thereof, may best be understood byreferring to the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 represents a partial schematic and sectional view of oneembodiment of my invention utilizing a representative means for gatingthe piezoelectric elements.

FIG. 2 represents a partial schematic and sectional view of anotherembodiment of my invention utilizing sonoluminescent material in asemi-liquid, dot form; and

ice

FIG. 3 representsa partial schematic and sectional view of still anotherembodiment of my invention wherein the piezoelectric elements are indirect cont-act with the sonoluminescent medium.

Referring now to FIG. 1, there is disclosed my novel luminescent panel12 having a liquid sonoluminescent material18 contained in a suitablecontainer wherein the' viewing side may be of transparent, glassy orplastic material 20. On the other side of the panel there is a thinmetallic, conducting plate 16 having piezoelectric elements 14 mountedthereon in the desired configuration. Where,

for example, it is desired that this device be utilized as a displaydevice in conjunction with a television receiver, elements 14 arearranged in rows and columns. Each element 14 has a wire 22 whichconnects it to a suitable gating device 10. To present a completelyoperable device, I have depicted herewith a beam switching tube havingthe usual gun and cathode in the neck thereof and anode plates 24 at theface. Conductive plate 16 is conne-cted through lead 26 to the cathodeof the gating device and when the proper potentials are applied to thedeflection plates, the generated beam will successively strike theplates 24, thereby completing a circuit across the respectivepiezoelectric elements 14. As soon as the circuit is completed and anelement 14 is energized, it vibrates at its natural resonant frequency,causing material 18 to luminesce.

In this connection it has been found that materials such as glycerol,dimethylsphthalate, nitrobenzol and ethylene glycol are particularlysuitable as sonoluminescent media. While these materials have been foundto work somewhat better than. others, it will be understood that othermaterials may also work equally as Well in different applications,

Referring now to FIG. 2, I have presented another embodirnent of mydevice wherein instead of the liquid medium of FIG. 1, thesonoluminescent material is a semiliquid medium. I have found that ifthe sonoluminescent material were embedded in a silica gel, for example,I would still be able to produce the same effect. In this embodiment,the gating device 10 is connected through lead 26 to plate 16.Piezoelectric elements 14, mounted on plate 16, are connected throughleads 22 to the gating device 10 in the same manner as previouslydescribed The sonoluminescent material is embedded in a silica gel anddeposited on the opposite side of plate 16 in the form of nodules ordots 22 which are in registry with corresponding elements 14. In thismanner, when an individual element 14 is energized, its energy istransmitted directly to the corresponding dot 22, which luminesces. Anyenergy that may be transmitted to an adjacent dot will be so severelyattenuated that no luminescence will be produced. While it has not beenshown, it will be obvious to those skilled in the art that a suitableprotective transparent covering may be placed over dots 22 to maintainthem in a semi-liquid state.

Referring now to FIG. 3, there is disclosed a single element of the typedescribed and it is to be understood that this is merely an enlarged,fragmentary cross-section of a panel. In this embodiment, thepiezoelectric element 14 is provided with a concave curved surface 24.This curved surface is placed in registry with an aperture, formed bywall 28, in conducting plate 16. As previously described, thepiezoelectric element is connected to the gating device 10 by means oflead 22, while lead 26 connects the common backing plate 16 to thegating device 10. Transparent wall 20 forms the container for thesonoluminescent medium 18. Thus, when the gating device 10 provides atriggering pulse to element 14, the element will vibrate at its naturalresonant frequency. However, the sound or vibrations will be focused atthe focal point of curved portion 24 which is well within the media 18to produce a spot of light. While it is realized that in some instancesbacking plate 16 may not provide suflicient rigidity, I have found thatby using selectively etchable glass of the type known as Fotoformproduced by the Corning Glass Works, an apertured mask 24, having goodstructural rigidity may be formed so as to have conically shapedapertures as shown.

While I have described what is presently considered the preferredembodiment of my invention, it will be obvious to those skilled in theart'that various changes and modifications may be made without departingfrom inventive concept contained therein, and it is, therefore, aimed inthe appended claims to cover all such changes and modifications as fallwithin the true spirit and scope of my invention.

I claim:

1. A luminescent panel comprising a conductive layer, a plurality ofpiezoelectric elements mounted on one side thereof; a sonoluminescentmedium on the other .side of the layer, said medium being luminescentupon vibration, and means causing selective piezoelectric elements tovibrate at their natural frequency to produce luminescence in the mediumin only those areas opposite the selected piezoelectric elements.

2. The device of claim 1 wherein the medium is a member of the groupconsisting of glycerol, dimethyl-phthalate, nitrobenzol, and ethyleneglycol.

3. The device of claim 1 wherein the medium is glycerol.

4. The device of claim 1 wherein the medium is dimethyl-phthalate.

5. The device of claim 1 wherein the medium is nitro benzol.

6. The device of claim l wherein the medium is ethylene glycol.

7. A luminescent panel comprising a conductive layer, a plurality ofpiezoelectric elements mounted on one side thereof, an equal pluralityof dots of sonoluminescent material mounted on the other side of thelayer and respectively corresponding to and in registry with thepiezoelectric elements, said dots being luminescent uponvibration, andmeans causing selected piezoelectric elements to vibrate at theirnatural resonant frequencies to produce luminescence in the dots whichare located opposite the selected piezoelectric elements.

8. The device of claim 7 wherein the sonoluminescent material is in asemi-liquid state.

9. The device of claim 8 wherein the sonoluminescent material is amember of the group consisting of glycerol, dimethyl-phthalate,nitrobenzol, and ethylene glycol.

10. The device of claim 8 wherein the sonoluminescent material isglycerol.

11. The device of claim 8 wherein the sonoluminescent material isdimethyl-phthalate.

12. The device of claim 8 wherein the sonoluminescent material isnitrobenzol.

13. The device of claim 8 wherein the sonoluminescent material isethylene glycol.

14. A luminescent panel comprising a conductive layer, having aplurality of apertures therein, an equal plurality of piezoelectricelements each having indentations in one surface thereof, saidindentations having given radii of curvature and focal points, saidplurality of piezoelectric elements being mounted on the conductivelayer with the indentations in registry with the apertures, asonoluminescent medium on the other side of the layer and extendingthrough said apertures into the indentations, and means causing selectedpiezoelectric elements to vibrate at their natural frequencies toproduce a shaped wave front at the focal point of each selectedpiezoelectric element and thereby produce luminescence in the medium atthe focal point thereof.

15. The device of claim 14 wherein the medium is a member of the groupconsisting of glycerol, dimethylphthalate, nitrobenzol and ethyleneglycol.

16. The device of claim 14 wherein the medium is glycerol.

17. The device of claim 14 wherein the medium is dimethyl-phthalate.

nitrobenzol.

19. The device of claim 14 wherein the medium is ethylene glycol. 20.The device of claim 14 further comprising an apertured support member,the wall of each of said apertures being sloped.

References Cited by the Examiner UNITED STATES PATENTS 2,508,098 5/1950Chilowsky 3153 2,733,216 1/1956 Eichholz et al. 25230l.2 2,816,23612/1957 Rosen.

2,895,917 7/1959 Gaunt 252301.2 2,936,416 5/1960 Hurvitz 32477 2,995,6828/1961 Livingston 315169 GEORGE N. WESTBY, Primary Examiner.

C. R. CAMPBELL, Assistant Examiner.

18. The device of claim 14 wherein the medium is

1. A LUMINESCENT PANEL COMPRISING A CONDUCTIVE LAYER, A PLURALITY OFPIEZOELECTRIC ELEMENTS MOUNTED ON ONE SIDE THEREOF, A SONOLUMINESCENTMEDIUM ON THE OTHER SIDE OF THE LAYER, SAID MEDIUM BEING LUMINESCENTUPON VIBRATION, AND MEANS CAUSING SELECTIVE PIEZOELECTRIC ELEMENTS TOVIBRATE AT THEIR NATURAL FREQUENCY TO PRODUCE LUMINESCENCE